One site noted her dress and matching coat were "elegant, but her headpiece was deemed to be a ludicrous addition, perching on her forehead at an impossible angle and detracting from her sophisticated outfit." PHOTOS: Famous royal weddings

Not everyone hated on Beatrice's hat.

"Yes, Beatrice's hat certainly deserves a Wall of It's own, but there were lots of great Runner-ups in the crowd too....let's not leave them out either. British women are gutsy...I take my hat off to them!! :D," wrote one fan on Facebook. PHOTOS: The 9 wackiest wedding celebrations

Treacy created 36 hats for the royal wedding, including for Camilla, the Duchess of Cornwall, Princess Eugenie, Princess Michael of Kent, Queen Anna-Marie of Greece, Victoria Beckham and Princess Mathilde of Belgium.